Hydraulic/pneumatic to electric transducer



March 7, 1967 c. w. YOUNGBLOOD 3,308,357

HYDRAULIG/PNEUMATIC TO ELECTRIC TRANSDUCER v Filed March 11, 1964 L 'f2 @El Z @1:2 50 (54 v/cs IN VENTOR,

United States Patent iiice 3,308,357 HYDRAULIC/ PNEUMATICI TO ELECTRIC TRANSDUCER Charles W. Youngblood, Royal Oak, Mich., assignor to Micromatic Hone Corporation, Detroit, Mich., a corporation of Michigan Filed Mar. 11, 1964, Ser. No. 351,013 11 Claims. (Cl. 317-246) This invention relates to transducers and more specifically to transducers of the type for providing an electrical signal in accordance with a fluid pressure signal.

In general, the transducer of the present invention is of the variable capacitance type actuable responsively to a iiuid signal and is an improvement on vthe type shown in the U.S. patents to M. M. Arlin, Nos. 2,635,748 and 2,908,980, and can be used with the electrical circuitry shown therein. In the transducer of the present invention novel actuating means for responding to a fluid pressure input signal are provided as well as novel means for providing adjustment and/or calibration of the output signal from the transducer.

It is a general object of this invention to provide a transducer of an improved construction for providing an electrical output signal varying in magnitude in accordance with variations in a fluid pressure input signal.

It is another object of this invention to provide a transducer of the above described type having novel means for responding to a fluid pressure input signal. It is still another object of this invention to provide a transducer of the above described type having novel means for providing adjustment and/ or calibration of the output signal.

Other objects, features, and advantages of the present invention will became apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a top elevational view of a preferred form of a transducer assembly embodying features of the present invention;

FIGURE 2 is a sectional view to increased scale of the transducer assembly of FIGURE l taken substantially along the line 2 2; A

FIGURE 3 is a top elevational view of a modified transducer assembly; and

FIGURE 4 is a sectional View to increased `scale of the modified transducer assembly of FIGURE 3.

Looking now to FIGURES l and 2, a transducer assembly i-s generally indicated by the numeral and includes metal, circularly shaped top and bottom members 12 and 14, respectively, having a metal, annular spacer member 16 sandwiched therebetween. The top and bottom members 12 and 14 and spacer member 16 are secured together by a plurality of bolts 18 and define thereby a housing having a substantially enclosed cavity 20. A flat, thin, fiexible, metal diaphragm member 22 is sandwiched between the lower member 14 and the spacer 16 and divides the cavity into two separate chambers 20a and 20b which are isolated from each other. As will be seen the diaphragm member 22 acts as a detiectable plate of a variable capacitor.

A stationary plate assembly 24 is located within the chamber 20a and includes a plastic support member 26 which has a metal plate member 28 fixed thereto. Three equally spaced bolts 30 are located on a central bolt circle and extend in clearance relationship through bores 32 in the top member 12 and have their enlarged heads located in counterbores 34. The bolts 30 have their threaded ends in threaded engagement with similarily threaded and spaced bores 36 in the plastic support member 26. An O-ring spacer 38 is located about each of the bolts 30 and is maintained under compression be- 3,308,357 Patented Mar. 7, 1967 tween the top member 12 and the plastic support member 26 whereby the bolts 30 are maintained in tension and unwanted movement of the stationary plate assembly 24 is prevented. The O-rings 38 are made of a resilient material such as rubber and hence are readily deformable. With the stationary plate assembly 24 thus supported, the fixed plate member 28 is located proximate to and in confrontation with the deflectiable plate member 22. The deiiectable plate member 22 and fixed plate member 2S defines a varia-ble capacitance the value of which depends upon the confronting areas of the plate members 22, 28, the spacing therebetween and the dielectric characteristics of the material therebetween. In the embodiment of FIG- URES l and 2 the dielectric is air. By manipulation of bolts 30, the distance between plates 22 and 28 can be varied; hence, the bolts provide means for initially selecting the desired capacity between plates 22 and 28. This adjustment is readily made against the resilience of the O-rings 38 which permit movement of the stationary plate assembly 24 while holding it in its selected position.

A bore 40 in the bottom member 14 is provided with a pipe thread and is thereby adapted to receive a fitting from a fiuid pressure line (not shown). The line could be connected to apparatus similar to that shown in the United States patent to Greening et al., No. 3,059,381, issued October 23, 1962, such that variations in the diameters of bores being measured result in corresponding variations in pressure in the fluid pressure line connected at bore 40. These variations in pressure, of course, result in similar pressure variations in the chamber 20b whereby the diaphragm plate member 22 is fiexed more or less in a direction relative to the fixed plate member 28; thus variations in the magnitude of the capacity between plates 22 and 28 are provided in accordance with variations in pressure in the chamber 20h. These variations can be sensed with apparatus as shown and described in the patents to M. M. Arlin, supra, and an appropriate calibration can be obtained. Note that by selective manipulation of the individual bolts 30 it is possible to selectively vary the orientation of the plane of the fixed plate member 28 relative to the deectable plate member 22 and to thereby selectively change the calibration.

A male coaxial connector 42, of a conventional construction, is mounted onto the upper member 12 at its outer surface and has its center conductor 44 electrically connected to the fixed plate 28 via a conductor 46. The shield or outer casing of the connector 42 is electrically connected to the exible plate 22 via the upper member 12, spacer member 16, and lower member 14. Thus a transducer assembly has been shown which is operative for providing a change in an electrical characteristic responsively to fluid pressure and which has means for supporting one of the plates of the capacitance assembly while permitting selective adjustment thereof relative to the other of the plates.

A modified transducer assembly 50 is shown in FIG- URES 3 and 4 and includes metal, top and bottom members 52 and 54, respectively, which are spaced apart by an annular spacer member 56. The top and bottom members 52 and 54 and spacer member 56 are held together by a plurality of bolts 58 and define thereby an enclosed chamber 60. An annular ring member 62 is located in chamber 60 and is supported upon the bottom member 54. The bottom member 54 and ring member 62 have confronting recesses which together define .a cavity 64 in which is located a capsule type receiver member 66, which will be described later. An annular sea'l 68 is located in cavity 64 at the juncture between the bottom member 54 and the annular ring 52 yand provides a seal therebetween.

A variable capacitance assembly '70 comprises fixed and movable elongated metal plate members 72 and 74, respectively, which are separated from each other by means of an insulator block 76 located at one end. The plate members 72, 74 and block 76 are held together within the chamber 60 and are mounted upon the upper surface of the ring member 62 via screws 78 whereby the plate members 72, 74 extend cantilever fashion, parallelly, radially inwardly of the ring member 62. rlhe plate members 72, 74 form the plates of a capacitor the capacity of which is determined by the confronting areas of each, the distance therebetween, `and the characteristics of the dielectric therebetween; in the embodiment of FIGURES 3 and 4 the dielectric is air.

The receiver member 66 is hollow and of a generally circular cross-section and is made of a flexible material such that upon the application of a fiuid pressure therein expansion of the member 66 occurs causing its central portion 79 to move axially an amount corresponding to the magnitude of this pressure. The receiver member 66 can be connected to apparatus similar to that described in conjunction with the discussion of the embodiment of FIGURES 1 and 2.

A pin 80 is fixed to the free end of movable plate member 74 and is located centrally of and in engagement with the central portion 79 of receiver member 66. The plate member 74 has a reduced section portion 82 near its fixed end to facilitate deflection of that member towards and away from the fixed plate member 72 responsively to the pressure in the receiver member 74 whereby the capacitance of the assembly '70 is varied in accordance with variations in that pressure.

The free end of the fixed plate member 72 extends beyond the movable member 74 and has secured thereat via screws 84 a plastic extension member 86. A screw member SS h-as an enlarged diameter portion 90` threadably engageaole and movable within aligned, threaded bores 92 and 94 extending through the bottom member 54 and ring member 62, respectively. The screw member 88 terminates at one end in a threaded reduced diameter portion 96 which is threadably engageable with a threa-ded bore 98 in the extension member 86. The fixed plate member '72 has a reduced section portion 100 near its fixed end to facilitate bending movement of that member. Thus as the screw member 88 is threaded within the bores 92, 94 it is simultaneously threaded into the bore 98. Since the pitch of the threads on portions 90 and 96 are different, and since the Ibottom member 54 and ring member 62 are fixed to each other, the xed plate member 72 Iwill be moved to or away from the movable plate member 74 a distance corresponding to this difference in pitch for each rotation of the screw member 88.

This is significant since the value of the capacity of the capacitance assembly 70 is quite sensitive to the distance between plate members 72 and 74 and hence the structure described above provides means for obtaining a fine adjustment for the initial value of capacitance. The end of the screw member 88 opposite the reduced diameter portion 96 is provided with a sl-ot 101 for receiving a tool whereby the screw mem-ber 88 can be turned.

A male coaxial connector 102, of a conventional construction, is mounted onto the upper member 52 at its outer surface and has its center conductor 104 electrically connected to the fixed plate 72 via a conductor 105 and an electrical terminal 106. The terminal 106 is held to the fixed plate member 72 by means of the bolt 7 8 which is insulated from the terminal 106 and the plate 72 via a plastic bushing 108. The shield or outer casing of the connector 102 is electrical-ly connected to the flexible plate 74 via ring member 62, bottom member 54, and spacer member 56. The modified transducer assembly 50 can be used with apparatus as shown and described in the patents to M. M. Arlin, supra, whereby an electrical signal can tbe provided having a magnitude varying in accordance with the magnitude of the capacity of the capacitance assembly 70 which in turn varies in accordance with the pressure in the receiver 66. As previously noted, with the apparatus of FIGURES 3 and 4, means are provided whereby a tine adjustment of the magnitude of the capacity can be selectively obtained.

While it will be apparent that the preferred embodiment of the invention disclosed is wel-l calculated to fulfill the objects above st-ated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or air meaning of the subjoined claims.

What is claimed is:

1. A variable capacitance gage assembly for providing a change in the magnitude of its capacitance in accordance with variations in the magnitude of a quantity being measured comprising: a first capacitance plate member, a second capacitance plate member spaced from said first plate member and being defiectable towards and away from said first plate member, means connected with said second plate member for -deflecting said second plate member a distance varying in accordance with the variations in the magnitude of the quantity being measured,

adjustment means connected to said first plate member and being selectively operable for moving said first plate member towards and away from said second plate memn ber whereby the capacity therebetween can be selectively adjusted, said adjustment means inclu-ding a threadably mounted screw member yand rigid connecting means fixed to said first plate member and connecting said first plate member and said screw member with said screw -member being rotatable relative to said connecting means and being selectively manipuable for moving said first plate member,

2. A variable capacitance gage assembly for providing a change in the magnitude of its capacitance in accordance with variations in the magnitude of a quantity being measured comprising: a housing assembly, a first elongated, capacitance plate member, a second elongated, capacitance plate member spaced from and underlying said first plate member and being detlectable towards and away from said first plate member, mounting means for fixing said first and second plate members to said housing assembly proximate to and in spaced relationship with each other, deflecting means connected with said second plate member for deflecting said second plate member a distance varying in accordance with the variations in the magnitude of the quantity being measured, adjustment means connected to said first plate member and being selectively operable for moving said first plate member towards and away from said second plate member to fixed positions whereby the capacity therebetween can be selectively adjusted, said adjustment means including a screw member threadably connected between said first plate mem-ber and said housing assembly, said adjustment means further including rigid connecting means connecting said first plate member and said screw member with said screw member being rotatable relative to said connecting means and said housing assembly, said screw member having first and second threaded portions with different pitches with said rst portion being threadably connected to said connecting means and with said second portion being threadably connected to said housing assembly and being selectively manipulatable for moving said first plate member toward and away from said second plate member in accordance with the difference between said pitches.

3. A variable capacitance gage assembly for providing a change in the magnitude of its capacitance in accordance with variations in the magnitude of a quantity being measured comprising: a housing assembly, a first elongated, capacitance plate member, a second elongated, capacitance plate member spaced from and underlying said first plate member and being deflectable towards and away from said rst plate member, mounting means for fixing said first and second plate members to said housing assembly proximate to and in spaced relationship with each other, defiecting meansvconnected with said second plate member for deflecting said second plate member a distance varying in accordance with the variations in the magnitude of the quantity being measured, adjustment means connected to said first plate member and being selectively operable for moving said first plate member towards and away from said second plate member to fixed positions whereby the capacity therebetween can be selectively adjusted, said adjustment means including a screw member threadahly connected between said first plate member and said housing assembly, said adjustment means further including rigid connecting means connecting said first plate member and said screw member with said screw member being rotatable relative to said connecting means and said housing assembly, said screw member having first and second threaded portions each with a different pitch with said first portion being threadably connected to said connecting means and with said second portion being threadahly connected to said housing assembly and being selectively manipuable for moving said first plate member toward and away from said second plate member in accordance with the difference between said pitches, said defiecting means comprising an enclosed capsule member for receiving a fluid pressure signal having a magnitude varying in accordance with the variations in the magnitude of the quantity being measured and for expanding and contracting in response to said fiuid pressure signal and means connecting said capsule member Vto said second plate member whereby said second plate ymember is deflected in accordance with the expansion and contraction of said capsule member, said housing assembly having means for holding said capsule.

y 4. A Variable capacitance gage assembly for providing a ,change in the magnitude of its capacitance in accordance with variations in the magnitude of a quantity being measured comprising: a housing assembly, a first capacitance plate member, a second capacitance plate member spaced from and underlying said first plate member and being defiectable towards and away from said first plate member, mounting means for fixing said first and second plate members to said housing assembly in spaced relationship to each other, defiecting means connected with said second pla-te member for deflecting said second plate member a distance varying in accordance with variations inthe magnitude of a quantity being measured, adjusta ment means connected to said first plate member and being selectively operable for moving said plate members towards and away from each other to fixed positions 1 whereby the capacity therebetween can be selectively adjusted, said defiecting means comprising enclosed chamber lmeans for receiving a fiuid pressure signal having a magnitude varying in accordance with the variati'ons in the magnitude of the quantity being measured and for excordance with variations in the magnitude of a quantity being measured comprising: a housing assembly, a first capacitance plate member, a second capacitance plate member spaced from and underlying said first plate member and being deflectable towards and away from said first plate member, mounting means for fixing said first and'second plate `members to said housing assembly in spaced relationship to each other, deflecting means connected with said second plate member for defiecting said second plate member a distance varying in accordance with variations in the magnitude of a quantity being measured, adjutment means connected to said first plate member and being selectively operable for moving said plate members towards and away from each other to fixed positions whereby the capacity therebetween can be selectively adjusted, said adjustment means including a screw member threadahly connected between said first plate member and said housing assembly, said adjustment means further including rigid connecting means connecting said first plate member and said screw member with said screw member being rotatable relative to said connecting means and said housing assembly, said screw member having first and second threaded portions with different pitches with said first portion being threadahly connected to said connecting means and with said second portion being threadahly connected to said housing assembly and being selectively manipuable for moving said first plate member toward and away from said second plate member in accordance with the difference between said pitches.

6. A variable capacitance gage assembly for providing a change in the magnitude of its capacitance in accordance with variations in the magnitude of quantity being measured comprising: a housing assembly, a rst elongated, metallic capacitance plate member, a second elongated, metallic, capacitance plate member spaced from and underlying said first plate member and being defiectable towards and away from said first plate member, mounting means for fixing in a cantilever fashion said first and second plate members at one end to said housing assembly proximate to and in spaced relationship with each other with said second plate member being held in direct electrical contact with said housing assembiy and including a plastic spacer member located between said plate members at said one end whereby said second plate member is isolated from direct electrical contact with said housing assembly, d'efiecting means connected with said second plate member for defiecting said second plate member a distance varying in accordance with the variations in the magnitude of the quantity being measured, a plastic arm fixed to the free end of said first plate member, adjustment means connected to said first plate member and being selectively operable for moving said first plate member towards and away from saidsecond plate member to fixed positions whereby the capacity therebetween can be selectively adjusted, said adjustment means including a screw member having a first, threaded portion having a thread with one pitch and being threadahly engaged with said plastic arm and having a second threaded portion having a thread with a different pitch and being threadahly engaged with said housing assembly, said screw member being selectively manipuable for moving said first plate member toward and away from said second plate member in accordance with the difference between said pitches, said deflecting means comprising an enclosed capsule member for receiving a fluid pressure signal having a magnitude varying in accordance with the variations in the magnitude of the quantity being measured and for expanding and contracting in response to said fluid pressure signal and means connecting said capsule member to said second plate member proximate its free end whereby said second plate member is defiected in accordance with the expansion and contraction of said i capsule member.

7. A variable capacitance gage assembly for providing a change in the magnitude of its capacitance in accordance with variations in the magnitude of a quantity being measured comprising: a housing assembly, a first capacitance plate member, a second capacitance plate member spaced from said first plate member and being defiectable towards and away from said first plate memher, said first and second plate members each having a surface in confrontation with the other, means connected with said second pla'te member for moving said second plate member a distance varying in accordance with variations in the magnitude of a quantity being measured, adjustment means connected to said first plate member and being selectively operable for moving said first plate member towards and away from said second plate member, said adjustment means including a plurality of screw members threadably connected with said first plate member and connected to said housing assembly and selectively manipuable for moving said first plate member and for selectively adjusting the plane of the surface of said first plate member, and resilient means located between said first plate member and said housing assembly for resiliently urging said first plate member toward said second plate member and for maintaining said screw members in tension.

8. A variable capacitance gage assembly for providing a change in the magnitude of its capacitance in accordance with variations in the magnitude of a quantity being measured comprising: a housing assembly, a rst capacitance plate member, a second capacitance plate member spaced from said first plate member and being movable towards and away from said rst plate member, said first and second plate members each having a surface in confrontation with the other, means connected with said second plate member for defiecting said second plate member a distance varying in accordance with variations in the magnitude of a quantity being measured, adjustment means connected to said first plate member and being selectively operable for moving said first plate member towards and away from said second plate member, said adjustment means including at least three screw members threadably connected with said first plate member and connected to said housing assembly and selectively manipuable for moving said first plate member and for selectively adjusting the plane of the surface of said first plate member, and each of a plurality of resilient O-ring members disposed about said screw members between said first plate member and said housing assembly for resiliently urging said first plate toward said second plate member and for maintaining said screw members in tension.

9. A variable capacitance gage assembly for providing a change in the magnitude of its capacitance in accordance with variations in the magnitude of a quantity being measured comprising: a housing assembly, a first capacitance plate member, a second flexible capacitance plate member spaced from and underlying said first plate member and beingdefiectable towards and away from said first plate member, defiecting means comprising enclosed chamber means for receiving a fluid pressure signal having a magnitude varying in accordance with the variations in the magnitude of the quantity being measured, said chamber means including said second plate member with said second plate member being defiectable towards and away from said first plate member in accordance with the magnitude of said fluid pressure signal as applied to one side of said second plate, said second plate having its opposite side located generally in a non-pressurized area, said chamber means being independent of said first plate member, adjustment means connected to at least one Iof said plate members and being selectively operable for moving said plate members relatively towards and away from each other to fixed portions whereby the capacity therebetween can be selectively adjusted.

10. A variable capacitance gage assembly for providing a change in the magnitude of its capacitance in accordance with variations in the magnitude of a quantity being measured comprising: a housing assembly, a first capacitance plate member, a second capacitance plate member spaced from and underlying said first plate member and being defiectable towards and away from said first plate member, said first and second plate members each having a surface in confrontation with the other, adjustment means connected to said first plate member and being selectively operable for moving said first plate member towards and away from said second plate member, said adjustment means including at least three screw members threadably connected with said first plate member and connected to said housing assembly and selectively manipuable for moving said first plate member to selected position relative to said second plate member and for selectively adjusting the plane of the surface of said first plate member at said selected positions, and each of a plurality of resilient O-ring members disposed about said screw members between said first plate member and said housing assembly for resiliently urging said first plate towards said second plate member and for maintaining said screw members in tension, and deflecting means comprising enclosed chamber means for receiving a fiuid pressure signal having a magnitude varying in accordance with the variations in the magnitude of the quantity being measured, said chamber means including said second plate member with said second plate member being defiectable towards and away from said first plate member in accordance with the magnitude of said fiuid pressure signal.

11. A variable capacitance gage assembly for providing a change in the magnitude of its capacitance in accordance with variations in the magnitude of a quantity being measured comprising: a housing assembly, a first metallic, capacitance plate member, a second metallic, capacitance plate member spaced from and underlying said first plate member and being defiectable towards and away from said first plate member, said first and second plate members each having a surface in confrontation with the other, mounting means for fixing said second plate member to said housing assembly in spaced relationship to said first plate member and in direct electrical contact with said housing assembly, adjustment means connected to said first plate member and being selectively operable for moving said first plate member towards and away from said second plate member, said first plate member connected to a plastic support member, said adjustment means including at least three screw members threadably connected to said support member and connected to said housing assembly and selectively manipuable for moving said support and first plate members to selected positions and for selectively adjusting the plane of the surface of said rst plate member at selected positions, and each of a plurality of resilient O-ring members disposed about said screw members between said support member and said housing assembly for resiliently urging said support and first plate members toward said second plate member and for maintaining said screw members in tension, defiecting means comprising enclosed chamber means for receiving a fluid pressure signal having a magnitude varying in accordance with the variations in the magnitude of the quantity being measured said chamber means including said second plate member with said second plate member being defiectable towards and away from said first plate member in accordance with the magnitude of said fluid pressure signal, said first plate member as supported to said housing assembly by said screws, support member, and O-rings being substantially, electrically isolated from said housing assembly.

References4 Cited by the Examiner UNITED STATES PATENTS 2,452,799 ll/l948 Speaker 317-246 X 2,751,530 6/1956 Armstrong 317-246 2,907,320 10/1959 De Weese 317--246 X 2,958,056 10/1960 Di Giovanni 317-246 X 3,222,581 12/1965 Lenfant 317-246 LEWS H. MYERS, Primary Examiner.

L. E. ASKIN, E. GOLDBERG, Assistant Examiners. 

1. A VARIABLE CAPACITANCE GAGE ASSEMBLY FOR PROVIDING A CHANGE IN THE MAGNITUDE OF ITS CAPACITANCE IN ACCORDANCE WITH VARIATIONS IN THE MAGNITUDE OF A QUANTITY BEING MEASURED COMPRISING: A FIRST CAPACITANCE PLATE MEMBER, A SECOND CAPACITANCE PLATE MEMBER SPACED FROM SAID FIRST PLATE MEMBER AND BEING DEFLECTABLE TOWARDS AND AWAY FROM SAID FIRST PLATE MEMBER, MEANS CONNECTED WITH SAID SECOND PLATE MEMBER FOR DEFLECTING SAID SECOND PLATE MEMBER A DISTANCE VARYING IN ACCORDANCE WITH THE VARIATIONS IN THE MAGNITUDE OF THE QUANTITY BEING MEASURED, ADJUSTMENT MEANS CONNECTED TO SAID FIRST PLATE MEMBER AND BEING SELECTIVELY OPERABLE FOR MOVING SAID FIRST PLATE MEMBER TOWARDS AND AWAY FROM SAID SECOND PLATE MEMBER WHEREBY THE CAPACITY THEREBETWEEN CAN BE SELECTIVELY ADJUSTED, SAID ADJUSTMENT MEANS INCLUDING A THREADABLY MOUNTED SCREW MEMBER AND RIGID CONNECTING MEANS FIXED TO SAID FIRST PLATE MEMBER AND CONNECTING SAID FIRST PLATE MEMBER AND SAID SCREW MEMBER WITH SAID SCREW MEMBER BEING ROTATABLE RELATIVE TO SAID CONNECTING MEANS AND BEING SELECTIVELY MANIPUABLE FOR MOVING SAID FIRST PLATE MEMBER. 